Pointer in the editor; new screenshots and an editor section in the README

Scenes for the screenshots come from export_scenes (src/scenes.rs) and are
taken with tools/screenshots.py in the Playwright image.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -22,7 +22,7 @@ An evil little dungeon game for the browser - in glorious pixels, in 3D, for fre
 </p>
 
 <p align="center">
-  <img src="docs/screenshots/title-battle.png" width="820" alt="The title screen with the endless bridge battle">
+  <img src="docs/screenshots/title-battle.png" width="820" alt="The title screen: the endless battle between a lava river and an underground river">
 </p>
 
 ---
@@ -63,7 +63,7 @@ with them, up to golden armour, a crown and a halo. With the level come abilitie
 to *step through shadows*, the chainbreaker to spin like a *whirlwind*.
 
 <p align="center">
-  <img src="docs/screenshots/bridge-battle.png" width="820" alt="A battle at a bridge over an underground river">
+  <img src="docs/screenshots/bridge-battle.png" width="820" alt="A battle on a tongue of rock between lava and water">
   <br><i>The knights brought a bridge. How thoughtful. Now they're bringing it back, one piece at a time.</i>
 </p>
 
@@ -98,6 +98,36 @@ caves, rival masters, and me, telling you the story. With tea.
   <br><i>A dwarf cave, master. Nice dwarves. Don't go too close. - And this is where every game begins: in the dark.</i>
 </p>
 
+<p align="center">
+  <img src="docs/screenshots/lava-light.png" width="820" alt="Lava lights up the dungeon, torches on stands in a big hall">
+  <br><i>Lava glows ten tiles wide, master, and my imps put torches on stands where the walls are too far away.</i>
+</p>
+
+## Build your own campaigns
+
+> *You want to torment heroes your own way? Fine. The* **campaign editor** *is right in the title menu - in the same
+> graphics as the game, no tools needed.*
+
+<p align="center">
+  <img src="docs/screenshots/editor-campaign.png" width="400" alt="The campaign graph: missions as cards, linked by next missions and branches">
+  <img src="docs/screenshots/editor-map.png" width="400" alt="The map editor on the 3D map with the zone tool">
+  <br>
+  <img src="docs/screenshots/editor-triggers.png" width="400" alt="Triggers of a mission: zone entered, line crossed, zone claimed, ...">
+  <img src="docs/screenshots/editor-blocks.png" width="400" alt="The block editor with message, objective, variable and spawn blocks">
+</p>
+
+- **Campaign graph**: missions as cards; drag arrows for the next mission and for branches (another goal reached
+  first leads elsewhere). Save as a file, online, and publish for every player on the server.
+- **Maps**: a random map rolled once per run of the campaign, or a painted one - start from the generator and paint
+  ground, rooms, veins, the core, portals, the hero gate, units, towers, traps, knight fortresses and rival masters,
+  with brush, rectangle, fill, mirroring and undo. Trigger zones are drawn right on the map.
+- **Scripts as blocks**, no code: a start script, victory and defeat checks, a clock, and triggers - zone entered or
+  left, line crossed, zone claimed or dug, units in a zone, timers, a unit or tower falls, values, rooms, spells,
+  slaps, research. Problems are marked red while you build.
+- **Test play** right from the editor, with the trigger log and the variables on screen; **co-op** for editor
+  campaigns. *Open the demo* in the editor shows every trigger at work. Details: [docs/CAMPAIGN_EDITOR.md](docs/CAMPAIGN_EDITOR.md),
+  [docs/MISSION_SCRIPTING.md](docs/MISSION_SCRIPTING.md).
+
 ## Meet the household
 
 <p align="center">